diff --git a/csharp/ql/lib/ext/System.Net.WebSockets.model.yml b/csharp/ql/lib/ext/System.Net.WebSockets.model.yml
new file mode 100644
index 00000000000..23a14504a57
--- /dev/null
+++ b/csharp/ql/lib/ext/System.Net.WebSockets.model.yml
@@ -0,0 +1,6 @@
+extensions:
+  - addsTo:
+      pack: codeql/csharp-all
+      extensible: sourceModel
+    data:
+      - ["System.Net.WebSockets", "WebSocket", True, "ReceiveAsync", "", "", "Argument[0]", "remote", "manual"]